The invention relates to a method for subsequently implementing a SIM functionality, with the help of which a mobile telephone is enabled to use a mobile radio network, in a security module.
Mobile phones usually are provided with a telecommunication card, which is formed as a chip card inserted in the mobile telephone. Such a chip card has the format ID-1 or ID-000 according to the international standard ISO 7810. Here a combination of the stated formats is often used, namely by integrating a card body of the ID-000 format as a break-off part into a card body of the ID-1 format and the chip being disposed in the area of the ID-000 card body.
The telecommunication card in particular serves for furnishing proof towards a mobile telephone service provider of an access authorization to the mobile radio network and is also referred to as subscriber identity module, abbreviated SIM. A definite subscriber identity is stored in the telecommunication card which is also referred to as international mobile subscriber identity, abbreviated IMSI. The subscriber identity is written into the telecommunication card within the framework of a personalization, which is carried out in a secure surrounding, before the telecommunication card is handed out to the user.
Based on the subscriber identity the mobile radio system can carry out an authentication and ascertain thereby, whether the mobile telephone is authorized to use the mobile radio system. In addition, the subscriber identity is necessary for allocating to the user of the mobile telephone, for example, the call charges charged for a telephone call.
Furthermore, the telecommunication card is provided with a number of further functions. These functions permit, for example, the storage of short messages, the storage of the latest dialed telephone number for a last number redial, the storage of telephone numbers in a personal telephone directory or the storage of abbreviated numbers with which the dialing operation is facilitated for frequently used telephone numbers etc.
From EP 0 920 684 B1 a method for the read-out and read-in of data is known which are stored on a chip card that has a microprocessor, a memory and an additional memory. The additional memory can be read out and written into in a manner which bypasses the operating system.
EP 0 981 803 B1 discloses a method for performing an electronic personalization and/or initialization of a chip card. The personalization and/or initialization is effected with the help of a first apparatus which contacts the chip card and a second apparatus which is in a data link with the chip card via the first apparatus.
U.S. Pat. No. 5,557,679 discloses a method for personalizing a SIM card. The card is introduced in a card reader, which via a communication network is connected with a central computer. The IMSI and an authentication key are transmitted in encrypted form from the central computer to the card reader. The card reader decrypts the received data and passes them on to the card in a manner which prevents a spy-out. This can be achieved, for example, by a double encryption of the data and performing a decryption within the card.